Problem: Simplify the following expression: $r = \dfrac{-p}{10} + \dfrac{-5p}{10}$
Solution: Since the expressions have the same denominator we simply combine the numerators: $r = \dfrac{-p - 5p}{10}$ Combine like terms: $r = \dfrac{-6p}{10}$ Simplify by dividing numerator and denominator by 2: $r = \dfrac{-3p}{5}$